Currants (Ribes spp)

How well established is this crop?

This crop has been grown commercially in the region for at least 20 years. Commercial returns, current growers and some level of regional based research is available to help those new to this industry.

Background

Because the growth patterns and requirements of blackcurrants, redcurrants and whitecurrants are similar, they will be treated as one in this datasheet.

Currants belong to the Ribes genus and have been grown in home gardens for many years. A commercial industry exists, providing process berries for jellies and flavourings for yoghurts and ice-cream. However, the most common use of currants (specifically blackcurrants) is for beverages. A commercial industry folded in the southern regions of New Zealand about 15 years ago. This was driven by several factors include a virus that affected the plants and some poor marketing. Growers that have stayed in the industry are doing very well in the current market. People are realising the health benefits, with high levels of vitamins and antioxidants being present in the fruit.

Winter Chilling and Frosts

Frosts do not seem to greatly effect currants.

Rainfall and Irrigation

Currants do not like drying out, so irrigation is essential, especially in inland areas of Otago and as the berries ripen. They swell dramatically in size in the last few weeks. Dry soil in this period will lead to undersize and poor quality fruit.

Using mulch will reduce the water loss from the soil and mean less irrigation is needed. Drip methods are the best, rather than overhead systems as they deliver water directly to the plants root zone, reducing leaf wetness and associated disease problems.

After harvest, many growers turn off any irrigation systems. This slows plant growth down and prevents them shooting away with new vegetative growth. Soft growth such as this, is very vulnerable to winter frosts and can result in plant death.

Wind

Like most high value crops, shelter from the wind is essential. This can take the form of natural tree shelter or artificial shelter using wind cloth. A good rule of thumb when designing shelter for this crop is to multiply the final height of the shelter by 10. Use that measurement as the distance you position your shelters apart. For example if you have 6m high shelter trees, you will need shelters every 60m.

If using natural tree shelter, make sure the shelters running east-west are deciduous. This will allow sunlight into the blocks in the winter. Position all shelters at right angles to the prevailing winds. Talk to your local nursery when deciding on the right tree type for your property. They may also be able to help with design.

Soil

Like most berry fruit, currants require very specific soil conditions to grow well in. A well drained soil with a good moisture holding capacity is the start as many feeder roots are near to the soil surface. Blackcurrants are also known to like good levels of organic matter in the soil.

Do not attempt to grow currants if your soil has a high clay content, as these soils tend to stay wet in winter and dry out in summer.

Fertility

Currants require reasonable levels of soil fertility as they tend to be cropped quite hard. Regular soil and foliage tests will quickly identify an deficiencies and this can be easily corrected with the addition of fertiliser.

Currants are susceptible to over fertilising because of the position of the feeder roots near the soil surface. Slow release fertilisers are commonly used by the new growers to get around this problem.

Weed Control

Because currants are a perennial, weeds are a major problem. The best time to control them is before planting, but as the bushes grow over the years they will come back into the blocks. Hand weeding with hoes is a good way to control these weeds but it is very time consuming. Using agrichemicals is faster but can be a risk because of the close proximity of the feeder roots to the soil surface, and contact with foliage.

Varieties

A range of varieties are available to the new grower. Contacting an established producer may take some of the guesswork out of selecting varieties suitable for Otago conditions.

Pests and Diseases

Currants suffer from a number of insect and fungal pathogens so a full spray program is recommended. The insects include currant clearwing and leafrollers (pheromone technology is available for these insects), mites and aphids. The disease pathogens include the reversion virus (this badly affected growers 15 years ago, however, new varieties are not susceptible), botrytis, powdery mildew and a leaf spot fungus.

Birds are a major problem as the berries start to change colour and ripen. They are best controlled by netting the blocks, shooting, or using other means of bird scaring.

Layout

Most currant blocks are planted to be machine harvested. This means 3m between the rows to allow for machinery access and plants 33cm apart within the row. If the plants are to be hand harvested the distance within the rows can be stretched out to 80cm–1m.

General Management

Doing your homework and selecting suitable cultivars for the area is the key to success with currants. Older varieties such as Magnus have been surpassed by newer selections, that have resistance to things such as the ‘reversion virus’. Once the cultivar has been selected getting the ground prepared is the next key task. Controlling perennial weeds such as thistles before planting will make management much easier later in the blocks life.

Once planted, the key tasks during the season are attending to irrigation needs, fungicide and insecticide spraying. Harvesting can be done by machine or by hand depending on the size of the block as the end use for the fruit. As the plants loose there leaves in autumn, weed control is needed and then some pruning. Removing the pruned canes form the block and burning them, reduces the chances of carrying over disease from one season to the next.

Harvest

Harvesting can be done by hand on smaller blocks. On larger areas machine harvestors are recommended. The fruit need to be chilled as soon as possible after harvest to extend its shelf life.

Equipment

Small blocks can be managed with a back-pack spray unit and general gardening equipment. Larger blocks are best managed with a small tractor unit for spraying, grass mowing, mulching, aerating etc as well as a machine harvestor.

Returns

Currant returns have fluctuated dramatically over the past 10-15 years. Returns are around $1.40 – 1.80/kg at present. This varies depending on the final use of the fruit i.e. process or fresh sales.

Contacts

If you are thinking of growing currants, talk to some local growers or contact the following organisations.

For soil fertility information contact
http://www.hortnet.co.nz/publications/guides/fertmanual/black.htm
www.hill-laboratories.com

For plants
Strawberry and NZ Berryfruit Propagators Ltd
11 Grenville Street
Lower Hutt
Ph 04 569 8263
e-mail propco@xtra.co.nz